Recommendation ITU-T G.9807.1 describes a 10-Gigabit-capable symmetric passive optical network (XGS-PON) system in an optical access network for residential, business, mobile backhaul and other applications. This system operates over a point-to-multipoint optical access infrastructure at the nominal data rate of 10 Gbit/s both in the downstream and the upstream directions. This Recommendation contains the common definitions, acronyms, abbreviations, conventions, general requirements, physical media dependent layer requirements, and transmission convergence layer requirements of the XGS-PON system. Amendment 1 to Recommendation ITU-T G.9807.1 (2016) contains necessary additional details and clarifications for the Recommendation, and provides regular specification maintenance. Amendment 2 continues the maintenance and evolution of ITU-T G.9807 (2016), and provides additional details regarding 40km operation, E2 budget class, OLT X/S tolerance mask definition, low latency traffic identification and other minor specification adjustments.